Variable compression ratio



Dec. 12, 1950 J, KRATZER Re. 23,307

VARIABLE COMPRESSION RATIO INTERNAL-COMBUSTION ENGINE Original Filed Aug. 12, 1943 IN V E NTOR Reissued Dec. 12, 1950 UNITED STATES PATENT. OFFICE VARIABLE COMPRESSION RATIO INTERNAL-COMBUSTION ENGINE Herbert J. Kratser, St. Louis, Mo.

13 Claims. (Cl. 123-78) Matter enclosed in heavy brackets II 1 appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue This invention relates to internal combustion engines and pertains particularly to the compression phase of the operation oi the engine, and in which, the principal object is to provide the conventional, multi-cylindered'internal combustion engine with simple and reliable means to greatly improve the over all thermal eiiiciency through the entire range oi throttle operation.

A further object is to provide the engine with means to decrease the combustion chamber volume oi respective cylinders, in approximately the same ratio that the absolute pressure in intake manifold decreases below the prevailing atmospheric pressure.

A still further object is to provide simple means permitting the adjustment oi the degree of compression of respective individual cylinders 01' an engine to the exact compression pressure desired.

Another object is to provide for the automatic cylinders l, each of which when the blocks are mounted and secured in place on the engine cylinder block or blocks 5, alining with respective work cylinders 6, and each cylinder 4 having an inverted piston I therein and a firing chamber 8, and connected to and extending upwardly from each piston is an adjustable link 9.

longitudinally disposed above the blocks 3 and supported in bearings Ill is a horizontal torque shaft II and keyed thereto is a lever I! having its short end l3 connected at H to one of the links I, and connected to the upper end or another oi' the links 9 is a lever ii of a dash-pot It, said lever also being keyed to the shaft ll.

15 The remaining links 9 01' respective pistons 'l are connected at their upper ends to respective short levers l1, keyed to the shaft Ii.

The long end of the lever i2 is provided on its free end with an adjustable pusher pin ill in enpositioning of the mechanism so that a mean 90 e sement w th e depression of a saddle II compression ratio will prevail as the engine is started, but which becomes fully eflective after a minimum time of the engine's operation.

Yet another object is to employ the degree or vacuum in the plurality of cylinders oi an engine, greatly augmented by the simultaneous decrease in the intensity of expansion pressures, to

' supply the motive force necessary to actuate the mechanism, and thereby to increase the compression ratio, resulting in an approximate constant absolute compression pressure at all times or env gine operation.

Another further object is to provide the firing chambers with resiliently actuated means to auon the upper end of an expansion coil spring 2|, the lower end of said spring being seated in a saddle 22 within an inverted piston 23 which is 'reciprocally mounted in a cylinder 24, supported 5 ,irom one of the blocks 3,

Upper and lower adjustable stops :5 and it respectively 01' a supporting bracket 21 are provided for limiting the swinging travel of the lever l2, said bracket being mounted on one of the blocks I.

Provision is made for maintaining an oil body in the space 29 beneath the piston 23 in the cylinder 24, through the oil line 29 from the oiling system (not shown) of the engine, when the entomatically vary the size or the chambers with l is op ra respect to the momentary torque loads oi the engine Other objects and advantages will appear as this description s and by reference to the drawing, in which- Figure 1 is a plan elevation of an eight-in-line, cylinder-ed internal eombustionenginqwith the invention applied thereto and forming part thereof.

Figure 2 is an enlarged fragmentary vertical sectional elevation, taken approximately on the line 1-2 of Fig. 1.

Referring by numerals .to the drawing. I desighates each of two auxiliary blocks used in this instance of showing and describing the inven- .tion, as applied to a conventional four-cycle internal combustion engine, said blocks being used in place oi the cylinder head blocks of the con- Iach block 3 is provided with its plurality 01 In practicing the invention, when the engine is stopped, the spring 2| will force the lever l2 upwardy against the stop 25, and consequently, all of the pistons I will be moved to maximum 40 lowered positions in the cylinders 4 by the rocking oi the shaft ii, thereby decreasing the size 0! the firing chambers l to points 01 greatest compression ratio, as would be required to approximate designed compression at idling operation of the engine, and at which position the adjustable stop 25 is fixed.

Simultaneous with the spring 2i forcing the lever it against the stop 25 th spring will force the piston 23 down in the cylinder 24 as-the oil 0 therebene'ath leaks back to the crank case ',through the oil line 19, and the free length of the spring will be approximately attained when the piston 23 seats against the bottom wall of the cylinder II, as shown in dotted lines in Pig. 2.

.ss The instant the engine is started, the compresation of the engine.

3 slon pressure against the pistons I will rock the shaft Ii and causethe spring end of the lover I! to bear against the unloaded spring II and start to compress it. Before any of the cylinders have fired, the lever it will have moved the approximate half-of its normal operative range of travel in compressing the spring to its initial operative tension, and upon succeeding revolutions of the engine crank-shaft with normal ignition of allof the cylinders l. the lever II will be completely moved against the bottom stop II, which limits the degree of outward movement of the pistons I, to positions of least compression ratio as required to provide the desired degree of compression, permitted by the fuel used. As the engine is [started] starved to idling, the lever 12 will be returned to a position determined by the initial spring tension.

The lever ll of the dash-pot It, being connected to the torque shaft ll, dampens out the inter-cyclic rocking movement impulses of the shaft ii, so that the mean average of the sum of the impulses will be required to be counterbalanced by the tension of the spring 21. The action of the tension of the spring 1i and.the dash-pot It, on the rocking of the shaft Ii, results in no movement of the shaft II and the pistons I linked thereto, unless achange in engine torque occurs.

During the initial idling period of the engine, the lubricating oil pump of the engine, will force oll up under the piston is, thus gradually moving the parth! compressed spring 2| outwardly until the piston 23 reaches the stop-ring 30, at the outer end of the cylinder 24, and at which time the lever II will be in a position near the upper stop 25, because the initial spring pressure at the spring end of the lever, will just balance the combined opposed turning effort on the shaft i I, consisting of the algebraic sum of the gas pressures of all of the pistons 1 on their respective short lever connections with the shaft I i. Thus, as the engine was idling, the oil pressure from the oil line 29 in raising the spring piston 23, also raised the spring end of the lever I! which caused the cylinder head pistons 1 to be moved to positions of minimum combustion chamber volume in respective firing chambers t for providing a maximum compression ratio for efllcient idling oper- When the engine throttle (not shown) is opened a small degree, the cylinder pressures of all cylinders during all cycles of operation increase a commensurate degree, as the vacuum created during suction strokes is less intense, the compression resistance greater, as well as the expansion pressures being greater.

In addition, there will be some increase in cylinder gas pressures while exhausting spent gas charges, thus the algebraic sum of instantaneous cylinder pressures will increase and result in rocking the shaft ii until the increased compression on the spring II will Just counterbalance the increased forces on the pistons "I, and simultaneously, as the lever I! moved away from the stop 25, the pistons 'i moved outwardly thus providing a slightly increased combustion chamber volume, as required to maintain approximate constant compression.

With the throttle wide open, the forces of cylinder gas pressures on the pistons 1, attain a maximum value and determine[s] the maximum spring tension necessary to Just counterbalance them (lever I! being slightly away from stop It) so that a minimum of drop from the maximum value, will be effective in causing the spring Ii to move the pistons I inwardly. Any throttling effect, incidental or intentional, will obviously cause a decrease fn the sum of gas pressures on the pistons I, with a proportionate decrease in the torque output of the engine, and the spring tension will then relocate the lever i! to Just balance the smaller forces on the pistons 'i and in so doing, relocate said pistons to positions of greater compression ratio. Thus, since the engine torque output is approximately directly proportional to forces on the pistons I. it is obvious that the automatioally selected compression ratio will vary approximately inverseLv proportionate to the torque output of the engine.

By utilizing the varying gas pressures as well as the varying vacuums in the' respective operating cylinders, an extremely simple, reliable and efficient mechanism is provided, whereby the corrective forces are large compared to the small inherent friction of the simple linkages used. Due therefore, to the simple mechanism disclosed, automatically selected, varying compression ratios, will instantaneously and reliably remain ad- Justed to the highest values as indicated for best thermal eiliciency, and should border-line knocking occur. the greatly increased combustion chamber pressures in effecting an enlargement of the combustion chamber volumes, inherently remove[s] the primary cause.

The adjustable links 9 permit exact equalizetion of individual cylinder compression, and the entire engine compression range can be adjusted up or down, and to meet final requirements for fine or minute changes, the adjustable pusher pin is on the spring end of the lever I2 is provided, which when adjusted will be effective on all of the pistons i and their respective cylinders 8, with respect to cyl nder compression.

The use of the dash-pot It in coniunction with the shaft II, will dampen-out pulsation at the lever i2, and the oil body beneath the piston 28 which is drained at times of engine shut-down for unloading the spring 2i, while not essential during normal operation, does assure a most prompt outward movement of the pistons i, during the first revolution of starting the engine, to eliminate possible excessive compression and pre-ignition at initial starting operation.

While an embodiment of the invention is here shown and described, obviously many others may occur to those sk lled in the particular art. I, therefore, do not limit myself to the details described, but claim as my invention all variations and modifications within the scope of the subjoined claims.

What I claim is:

[1. A cylinder for an internal combustion engine having a movable wall with manually adjustable means therefor, and automatically actuated means cooperable to move said wall between adiustably fixed positions] [2. A cylinder for an internal combustion engine having a manually adjustable movable wall in axial alinement with the cylinder, automatically actuated means cooperable to move said wall to decrease or increase the firing chamber of the cylinder and a pair of adjustable limiting stops cooperable with said means] [3. A cylinder for an internal combustion engine having a manually adjustable movable wall, and spring actuated means cooperable to move said wall between predetermined positions] [4. An internal combustion engine having a cylinder with a, manually adjustable movable wall to move it between fixed predetermined positions.]

is. A multi-cylindered internal combustion engine having a manually adjustable-movable wall forming a part of the firing chamber of each cylinder, and automatically actuated means cooperable to move all of said walls either inwardly or outwardly to vary distances in respective firing chambers] [6. A muiti-cylindered internal combustion engine having manually adjustable movable wall forming a part of the firing chamber .of each cylinder, and spring actuated means cooperable to move all of said walls either inwardly or outwardly to vary distances in respective firing chambers] ["I. A multi-cylindered internal combustion engine having a manually adjustable movable wall in axial alinement with respective cylinders and forming a part of the firing chamber of each cylinder, and resiliently actuated linkage cooperable to move all of said walls either inwardly or outwardly of respective cylinders] 8, A multi-cylindered internal combustion engine having manually adjustable cylinderheads, spring actuated linkage cooperable to-move said heads varying between adlustablyfixed stops, and a pulsationeliminator cooperable with said linkage.

9. A multi-cylindered internal combustion engine having movable cylinder heads, a rock shaft,

individually adjustable linkage connecting said heads to the rock shaft, and a spring actuated lever connected to said rock shaft having adjusting means at one end thereof.

10. A multi-cylindered internal combustion engine having movable cylinder heads, a rock shaft, individually adjustable linkage connecting said heads to the rock shaft, a spring actuated lever connected to saidjrock shaft having adjusting means at its extending end, and a fluid actuated piston cooperable with the spring of said lever.

11. A multi-cylindered internal combustion engine having movable cylinder heads in' axial alinement with respective cylinders, a rock shaft,

individually adjustable linkage connecting said" heads to the rock shaft, a spring actuated lever secured on said rock shaft, and apair of adjustable stops cooperable with said lever.

12. A multi-cylindered internal combustion engine having movable cylinder heads, a rock shaft,

individually adjustable linkage connecting said heads to the rock shaft, a lever secured to said rock shaft, a fluid cylinder, a piston in said cylinder, and a coil spring cooperable at one end with said piston and at its other end with said lever.

13. An internal combustion engine having a cylinder and a communicating firing chamber, a movable head in said firing chamber, a lever connected to said head, a cylinder having an oil pressure supply source, a piston in said oil cylinder adapted to be actuated by the oil pressure therein, a coil spring interposed between said lever and said piston, and a piston stop at the outer end of said oil cylinder.

[14. A cylinder for an internal combustion engine having a movable wall, automatically actuated means cooperable to move said wall to positions intermediate its movable length, and other means effective on said first means during starting of the engine] pression ratio internal combustion engine. con-' sisting of the automatic selection of a predetermined minimum compression ratio for the duration of the engine starting operation. and of subsequently [and] automatically selecting, directly by combustion chamber pressures at all engine speeds and independently of intake manifold pressures, compression ratios approximately inversely proportionate to the developed engine torque.

[16. A cylinder for an internal combustion engine having a movable wall, spring actuated means cooperabie to move the wall to decrease or increase the firing chamber of the cylinder, and automatic means cooperable to increase the spring pressure of said first means] [17. A multi-cylindered internal combustion engine having manually adjustable cylinder heads, and fixed stops between which said heads are automatically positioned.]

[18. A multi-cylindered internal combustion engine having respective cylinder heads, a rock shaft, and adjustable linkage connecting said heads to the rock shaft] [19. An internal combustion e ne having a cylinder and a communicating firing chamber, a movable head in said firing chamber, a spring actuated lever cooperable with said head, an adjustable stop to limit outward movement of said head, and manuall adjustable means located between said head and said lever.]

[20. An internal combustion engine having a cylinder and a firing chamber, a movable head in said firing chamber, a lever, manually adjust starting operatiom'und o! subsequently and automatically selecting higher compression ratios as determined directly by combustion chamber pressures independently of intake manifold pressures.

22. In an internal combustion engine, a cylinder having a movable wall, a device'acting automatically when the engine is starting to exert minimum thrust on said wall thereby prosiding a'minimum compression ratio in said cylinder, and means acting automatically and independently of the gas pressure in said cylinder, and independently of intake manifold pressures when the engine is running normally to increase the thrust of said device on said wall.

23. An internal combustion engine having a working cylinder and a firing chamber, a movable head in said firing chamber, a lever, manually adjustable means connecting said lever to said head, a cylinder having a fluid pressure sup-" ply source other than the pressure in said working cylinder, :1 piston in said fluid cylinder adapted to be actuated by the fluid pressure therein, and a spring interposed between said lever and said piston.

24. In an internal combustion engine having a plurality of cylinders with individually movable cylinder heads, a spring with associated individual connections to each head urging all of said heads inwardly of the cylinders against the cylinder gas pressures, a seat for said spring cylinder heads, a common spring with associated individual connections to each head urging all ojsaid cylinder heads inwardly o] the cylinders against the cylinder gas pressures, a seat for said spring movable to a retracted low-tension spring position for engine starting and-t0 an advanced higher-tension spring position for normal engine operation, a chamber for said seat, and fluid supplied to said' chamber under pressure provided automatically by the operation of the engine to move said seat from said retracted engine-starting position to said advanced engine-operating position.

26. An engine as described in claim 24 in which each individual cylinder head connection positively positions the head relative to the common urging spring, there being means in each connection for varying the relative position of the head and the spring.

HERBERT J. KRATZER.

REFERENCES CITED The following references are of record in the file of this patent or the original patent:

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